使用Object.DefineProperty并访问私有作用域中的变量 [英] Using Object.DefineProperty and accessing a variable in private scope

问题描述

以下不工作，从我的getter，我看不到在'class'Person中定义的 _nickname 。

The following doesn't work, from my getter, I can't see _nickname defined in the 'class' Person.

var Person = function (args) {

    var _nickname = '';
    if (args === undefined || args === null) {
        return;
    }
    if (args.nickname !== undefined && args.nickname !== null) {
        _nickname = args.nickname;
    }

}

Object.defineProperty(Person.prototype, "nickname", {
    get : function () {
        return _nickname;
    }
});

var x = new Person({
        nickname : 'bob'
    });

console.log(x.nickname);

如何完成这个？
是否有一种方法可以从函数的原型中添加_nickname到原型中？

How should one go about accomplishing this? Is there a way of adding _nickname to the prototype of Person from within its function?

推荐答案

是否有一种方法可以在函数的原型中添加_nickname到原型中？

Is there a way of adding _nickname to the prototype of Person from within its function?

如果你的意思是 Person 构造函数，确定（虽然在我看来它看起来不是很优雅）：

If you mean the Person constructor, sure (although in my opinion it doesn't look very elegant):

var Person = function (args) {
    var _nickname = '';
    if (args === undefined || args === null) {
        return;
    }
    if (args.nickname !== undefined && args.nickname !== null) {
        _nickname = args.nickname;
    }
    Object.defineProperty(this, "nickname", {
        get : function () {
            return _nickname;
        }
    });
}

var x = new Person({
    nickname : 'bob'
});

console.log(x.nickname);

http://jsfiddle.net/JEbds/

在这种情况下，您的getter只是另一个闭包，因此它可以访问 _nickname 。它不是在原型，你需要一个自己的属性来完成这一点。

In this case, your getter is just another closure, so it has access to _nickname. And it's not on the prototype anymore, you need an own property to accomplish that.

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